In the prior art, plasma reactors come in a variety of shapes, e.g. parallel plate and barrel types, and a variety of capacities, e.g. single wafer and batch. Typically, the reactor comprises a quartz, aluminum, or stainless steel chamber with aluminum electrodes positioned therein. In a recent advance in the art, as described in U.S. Pat. No. 4,209,357, a single wafer, parallel plate reactor is provided with an interior or upper plasma electrode which serves both as an RF (radio frequency) electrode and as a gas manifold. While providing increased uniformity and other advantages, the reactor is expensive to make due to the precise machining and alignment of the various parts which make up the electrode/manifold.
The processes run in plasma reactors have become more complex and use a variety of gases. As is known, a plasma contains the source gas or gases as well as intermediate products and by-products. Sometimes a successful process is obtained by only slight shifts in the chemical balance in the reactor. A problem exists in that the chemicals used or found in a process can chemically attack the materials used to make the chamber. Another problem is that the chamber, particularly the electrodes, is subject to physical attack by the plasma, e.g. what is known as back sputtering. Yet another problem is that certain materials react to form coatings on parts of the chamber, particularly the electrodes. These three problems combine for a fourth wherein subsequent operations, particularly with different chemicals, cause deposits or materials from the chamber to deposit on the semiconductor wafer therein, contaminating it, or to upset the chemical balance of the reaction.
These problems can be minimized by careful choice of materials and reagents, as well as routine cleaning of the chamber. This makes ease of assembly and disassembly an important feature of a reactor, both for cleaning and for changing at least the electrode materials.
In view of the foregoing, it is therefore an object of the present invention to provide an improved plasma reactor which is more easily assembled and disassembled.
Another object of the present invention is to provide a plasma reactor having readily removable electrodes.
A further object of the present invention is to provide a plasma reactor having interchangeable electrodes of different materials, with one set being chosen for a particular process.
Another object of the present invention is to provide a plasma reactor having electrodes coated with a material resistant to the plasma reaction.
A further object of the present invention is to provide a plasma reactor having electrodes coated with a material intended to contribute to the plasma reaction.
Another object of the present invention is to provide a plasma reactor having interchangeable electrodes of the same material for reducing the downtime associated with cleaning the reactor.
A further object of the present invention is to provide an improved plasma reactor having an electrode/manifold member of simplified construction.